The Collaborative International Dictionary of English v.0.48:

Dietary \Di"et*a*ry\, a.
   Pertaining to diet, or to the rules of diet.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dietary \Di"et*a*ry\, n.; pl. Dietaries.
   A rule of diet; a fixed allowance of food, as in workhouse,
   prison, etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dietary
    adj 1: of or relating to the diet; "dietary restrictions" [syn:
           dietary, dietetic, dietetical]
    n 1: a regulated daily food allowance